Overview

This workshop has arisen from the need and desire of experimentalists
working toward implementations of various quantum information processing
tasks to interact with mathematicians on the one hand, and mathematicians
working in quantum information or on its periphery to participate
in attempts to implement quantum computation and communication technologies
on the other. Thus, by its very nature this workshop is heavily
interdisciplinary. It is hoped that this event, held at the Institute
for Quantum Computing in Waterloo, will lead to collaborations between
scientists that would not have had the opportunity to interact otherwise.
Some potential interaction points are discussed below.

Experimental quantum information aims to develop physical systems
that can exhibit the requisite quantum properties as well as methods
for controlling and characterizing these systems. This is a very
challenging task that involves significant mathematical and statistical
issues. Quantum properties, such as entanglement and superposition,
are notoriously fragile. To harness these properties, two seemingly
contradictory constraints are required: the systems must be completely
isolated from their environment to fight decoherence, yet amenable
to precise and rapid control by outside forces. Despite these constraints,
several physical systems are being intensively investigated and
rapid progress has been achieved over the last several years.

For example, entanglement is a critical quantum resource in most
quantum information applications. Experiments with trapped ions
have demonstrated 6 and 8 ion entangled states, where the 6 ion
states have been used for quantum-enhanced phase measurements. Optical
experiments have demonstrated key entangled states, known as graph
states, in up to 6 optical photons. Nuclear magnetic resonance (NMR)
experiments have demonstrated the production of 12 qubit pseudo-pure
states; and recently a pair of superconducting qubits has, for the
first time, been entangled. Key quantum logic gates and even small
quantum computing algorithms have been demonstrated in several of
these systems.

Quantum cryptography is arguably the most advanced quantum technology.
This particular technology is dominated by optical implementations
since photons can be distributed over large distances with low decoherence.
Driven by improvements in entangled-photon source and detector technologies,
quantum key distribution has been demonstrated over 100km in both
fibre and free-space quantum channels. Several important questions
remain in the theory of quantum cryptography and will have important
consequences for the technology. Quantum key distribution has been
shown to be secure under, as of yet, unrealistic conditions. Can
we develop a working experimental system and prove that it is unconditionally
secure even with all of its real world imperfections? Quantum key
distribution systems can only tolerate a certain amount of errors
before their security is potentially compromised. However, there
remains a gap between the error rate of known secure systems and
systems which we know are not secure. Can we develop protocols to
close this gap and yield systems which are able to tolerate higher
error rates, or achieve higher bit rates?

Tentative Workshop Schedule

Monday August 10

Theme: Tomography

9:00-9:50

Registration and coffee

9:50-10:00

Opening remarks

10:00-10:50

Robin Blume-Kohout (Perimeter Institute)Tomography: What is it good for?

10:50-11:10

Break

11:10-12:00

Aephraim Steinberg (University of Toronto)Measuring quantum states in the presence of fundamental symmetries